With Well Capped, How Long Will The Oil Linger?The Gulf of Mexico has a few ways of cleansing oil from its waters: it hosts legions of microbes adapted to dine on natural oil seepages, and its warm water temperatures favor the evaporation of oil. But scientists say it's still too early to know how long it will take the Gulf to recover.

The Gulf of Mexico has a few ways of cleansing oil from its waters: it hosts legions of microbes adapted to dine on natural oil seepages, and its warm water temperatures favor the evaporation of oil. But scientists say it's still too early to know how long it will take the Gulf to recover.

Denise Reed, interim director, Pontchartrain Institute for Environmental Sciences; professor, Department of Earth and Environmental Sciences, University of New Orleans, New Orleans, La.

JOE PALCA, host:

This is SCIENCE FRIDAY from NPR. I'm Joe Palca, in for Ira Flatow.

Several weeks ago, BP capped the leaky well in the Gulf, and for the time being the gushing has stopped. A permanent fix may be on the way. Now BP and government officials may be able to stop calculating their what-if, worst-case scenarios and just focus on the dirty work of cleaning up the oil.

There are some natural conditions that will help with the cleanup. For example, the water in the Gulf is pretty warm right now, in some places in the mid-80s, and those higher temperatures mean the oil will evaporate faster.

And the Gulf is home to legions of microbes adapted to feast on the oil that naturally seeps from the sea floor. So with any luck, those microbes will be hungry.

Just how long remnants of the oil will lurk in marshes and sandbars or in underwater sediments is still up for speculation, but one thing's for sure: Chemists, biologists, ecologists and toxicologists will be studying the Gulf to gain a better understanding of how nature response to a disaster like this.

How much they have learned so far and what they hope to get in the future is our topic for the first part of this hour. So give us a call. Our number is 800-989-8255, that's 1-800-989-TALK. If you're on Twitter, you can tweet us your questions by writing the @ sign, followed by Scifri. If you want more information about what we'll be talking about this hour, go to our website at www.sciencefriday.com, where you'll find links to our topic.

And now let me introduce my guests. First, Christopher Reddy, he's an associate scientist of marine chemistry and geochemistry at the Woods Hole Oceanographic Institution in Massachusetts. He joins us from the studios of WCAI in Cape Cod. Welcome to SCIENCE FRIDAY, Dr. Reddy.

PALCA: Good afternoon. And my other guest is Denise Reed. She is the interim director of the Pontchartrain Institute for Environmental Sciences at the University of New Orleans and a professor in the Department of Earth and Environmental Sciences there. She joins us from the studios of WWNO in New Orleans. Welcome to SCIENCE FRIDAY, Dr. Reed.

Dr. DENISE REED (University of New Orleans): Thanks, Joe.

PALCA: So Dr. Reddy, let me start with you. What's going to happen to the oil out there? Are we going to know that this happened 40 years from now, this disaster in the Gulf?

Dr. REDDY: I'm not quite sure. I mean, certainly a lot of oil has been released into the environment. Nature has certainly responded and helped by evaporating the oil.

I think the key question is if we find oil that's 40 years from now, what percentage of it is of the relative release? So I think we want to kind of focus more on how much is going to be gone and how much is going to be gone in a year and two years and three years and four years than perhaps some trace evidence in four decades, which may not have much of an impact.

PALCA: So is there a good way to measure how the oil is, how much oil there is today and next year, and I mean is that being measured?

Dr. REDDY: Oh, yeah. There's a significant effort that's going on underway of collecting a variety of water samples, sediment samples, tissue samples, that will help provide some insight as to how much oil resides in each one of those matrices.

Perhaps what's even more important is that oil is a complex mixture of molecules, and each one of those molecules has a certain different behavior, and within that behavior provides clues as to certain processes, like evaporation or microbial degradation that's occurred on that oil.

And so not only can we tell how much oil there's been in looking at a sample -we can tell what's happened to it, and it actually has a story within itself.

PALCA: I see. Well, let me turn to you, Dr. Reed. What are we seeing so far? How would you characterize the damage, and how much are the wetlands, have badly have they been affected?

Dr. REED: Well, I think overall I'd say we've been very lucky so far, and I hope our luck is going to hold. We have some oil in the wetlands. We have, as you know, a very fragmented coast. People describe it as like a jigsaw puzzle with pieces missing. It's very convoluted, very gappy, lots of places for the oil to go and go in and out with the tide.

And so we've had some on the beach, but what has got to the area behind the barrier islands, into the bays, has some of that has also got into the wetlands.

The good thing about this is that the spill location is a good way offshore, 50 miles offshore, and so the oil actually has to travel a good distance before it reaches the most sensitive of the environments that we have at the coast, the coastal wetlands.

And as Chris just described, an awful lot of things can happen to that oil in that journey in terms of its degradation. So by the time the oil gets to the marshes, it's probably not toxic in the sense that it's going to just kill them on contact.

And so the real issue, as far as the wetlands are concerned, as far as those marsh grasses, is how much oil there is covering them. Can you still see some green? And for the most part, if you fly over coastal Louisiana, it's still mostly green.

PALCA: Really? So even if there's some oil there and even some oil on some of the grass, there's a chance that the grass in large will survive.

Dr. REED: Absolutely. One of the things you have to remember when you work on wetlands is that there's as much below the surface as there is above the surface.

You know, we think of the grass as the green part that we can see, but the roots and rhizomes below the surface are where the energy reserves really are for these plants.

And so these plants are also great adapted. They're really well-adapted to these environments where they live. The soils are wet and smelly, you know, when you go walking through them, right. There's decomposition going on there. There's not a lot of oxygen in that soil.

But the plants transmit oxygen from the leafy green part of the plant down to the roots, and that's how they manage to live in the wetlands. And so as long as there's green at the surface, and that oxygen transmission process can still continue down to the roots, then the plant has a good chance of surviving.

One of the things that has been observed just recently, given that this event has been going on now for 100-odd days, is that some of the plants that were initially oiled and looked fairly brown at the surface have started producing new green shoots.

What this tells us is that they are they've got a lot of reserves still left down there and that there's some energy, if you like, in the roots and rhizomes that can still fight back and put some green shoots out.

And they do that because they have to get that oxygen down to the roots. That's their survival mechanism, if you like.

PALCA: Right. So maybe I mean, I've heard a lot of reports of people running around in marshlands and trying to soak up this oil, but it sounds like you're saying that the grasses might have their own mechanisms that worked even better than anybody can do trying to help them.

Dr. REED: The grasses are pretty good. Yeah, nature's pretty good at this, as well as the microbial degradation that occurs at the surface of the marsh.

However, if the plants really are totally covered in oil, then it's possible that they may not be able to come back. If the whole plant is covered in some of the sticky black masses that we saw early in the event, then that could be bad.

But if you look at the whole scale of things, if you think about the whole coast of Louisiana, we have millions and millions of acres of coastal wetland, and so if you imagine this jigsaw puzzle, if you like, with the pieces missing in a corner, and the oil comes in, it doesn't penetrate across the whole picture of the landscape. It just gets caught around the edge - because the grass is actually very good at trapping the oil at the edge.

The tide in Louisiana only goes up and down by about a food or maybe two feet normally, and so even at high tide the plants are still sticking up out of the water. So when the oil floats in on top of the water, the edge of the grass captures it.

So what you see when you fly over the marsh often is a band of oiling - only, say, three, four, five feet wide at the edge, and then the marsh further in the back is still really untouched.

PALCA: Okay. Let's take a call now and go to Rachel(ph) in Long Beach, California. Welcome to SCIENCE FRIDAY. You're on the air.

RACHEL (Caller): Okay, I am a Master's student actually studying wetland ecology, and I was just curious - we're talking a lot about how long the oil is going to stay in the system. But I was wondering if there was any interest in research or even any funding from BP for the really long-term studies for even after the disturbance is gone, how the ecology of the region is going to be affected.

PALCA: Okay, Rachel, good question. Chris Reddy, let me ask you about that. You are interested in long-term survival rates and issues.

Dr. REDDY: Yeah, I've worked on several spills that have occurred 35 and 40 years ago, where you can still see some trace levels of oil and impacts. I suspect, and I'm not quite sure of it, but I suspect that the government, along with the responsible party, in this case British Petroleum, will put a use what they call set-asides, where they will set aside an area that was oiled and let it be and see - use it as a natural living laboratory.

I haven't heard if they've chosen any areas, but I know there's discussion of that.

PALCA: I think we just call them BP now. So I don't think they have any national association in their name any longer. But that's okay. So okay, you've been studying spills, you know, that go back 30 or 40 years. You had one in your neck of the woods in 1969. What's been now we're in 2010. What's been the effect of that?

Dr. REDDY: Well, 40 years later, you, if you take a shovel, you can still see and smell oil a couple inches below the surface, and you know, that's noteworthy that nature for some reason, you know, got snagged in that respect where you can still smell and still analyze oil in this region.

What's more important to perhaps put in the context is that of the oil that's spilled, and it was a pretty devastating spill, .02 percent of the oil that originally spilled can be found. And it's only a very small area that was originally oiled that still is persisting.

So you have to put this all in the context of yes, oil can persist for a long time, but how much, to what extent and to the damages that will occur are just as important.

PALCA: Right, and has this I mean, the fiddler crabs have had some damage to their ecosystem. Isn't that right?

Dr. REDDY: Yeah, in one location where we studied in 1969, small crabs who burrow down below to avoid predators and also help aerate the marsh can't they actually smell the oil. They're better than any of our chemical instruments we have in our lab, and they avoid the oil, and then they can't avoid predators.

And so the fiddler crabs are less abundant in this very small oiled area, and in fact they are also, for lack of a better term, drunk. The residual oil can act like a narcotic. And so they don't move as fast when they're stimulated.

PALCA: We're talking with Christopher Reddy. He is an associate scientist of marine chemistry at the Woods Hole Oceanographic Institution. And Denise Reed, she's the director of - or interim director of the Pontchartrain Institute for Environmental Sciences at the University of New Orleans. We're talking about the long-term consequences of this - well, the long and short-term consequences of the oil spill in the Gulf of Mexico.

We're taking your calls at 1-800-989-8255. We've got a short break, but we'll be coming back to talk more about the cleanup, how it's going and what we can expect in the future. So stay with us.

(Soundbite of music)

PALCA: From NPR, this is SCIENCE FRIDAY. I'm Joe Palca. We're talking about the oil spill cleanup this hour with my guests Christopher Reddy - he's an associate scientist at the Woods Hole Oceanographic Institution in Massachusetts - and Denise Reed. She's a professor in the Department of Earth and Environmental Sciences in New Orleans, at the University of New Orleans.

And let's take a call now and go to Jerry, Jerry in Tallahassee, Florida. Welcome to SCIENCE FRIDAY. You're on the air.

JERRY (Caller): Thank you, Joe. I'm curious about I'd like some more information about these oil-eating microbes. I can see this whole event becoming a fertile field for science fiction writers. And you mentioned that these microbes actually eat the oil. What happens do they ever become sated? Would they mutate? Are they like the fiddler crabs? Could they get drunk on it, or what's tell us more about those.

PALCA: Okay, Chris Reddy, what about that?

Dr. REDDY: Sure. Any run-of-the-mill, self-respecting bacteria would love to eat oil. It's the equivalent to butter for it's got a high caloric content, just and that's why we use it to power our cars.

I wouldn't worry too much about these bacteria. Any aquatic body, even far, far away from the Gulf of Mexico, if you dosed it with some oil in the right conditions in the right way, you will get them to eat the oil.

In the Gulf of Mexico, there will be some response, and the bacteria will eat some fraction of the oil. The key thing you have to remember about bacteria and eating oil is they act a lot like teenagers. They do it on their own timescale, like for a chore. They do it on their own timescale.

They usually do the easiest thing first, and they very rarely clean the whole job up. So they will play an important role in terms of our natural capacity to clean up the oil.

I wouldn't worry about science fiction aspect. When the food's gone - or in this case, you also have to remember that they'll eat the low-hanging fruit. There's some molecules that are pretty tasty, and then there are other molecules that are avoidable. And so they'll just leave them behind.

But I think we're pretty safe. The algae are our friends in this. I mean, the microbes are our friends, but they're certainly not going to be enemies down the road.

PALCA: Okay. Jerry, thanks very much for that question.

JERRY (Caller): Thank you.

PALCA: Okay. Denise Reed, can I ask you, you mentioned that the wetlands, you know, there's a lot of muck and decomposing stuff, which I presume has a lot of microbes in it. Is - do they play any role in cleaning up the marshes, or is there something else going on there?

Dr. REED: Well, essentially, the same process that's going to break down the oil in the marsh is going to break down the oil that's out in the Gulf of Mexico, or out in the open water, these fundamentally, you're just breaking down organic matter, and that's the kind of process that goes on here, you know, 24-7, 365, very, very actively.

This is a very warm environment. As you mentioned, the temperature of the water is well over 80 degrees already, and in the near shore waters, in the shallower waters, it can definitely be even warmer than that.

So we've got a very, very biologically productive system here, and so, as Chris says, this is just another source of food. And so the consumers in this, the bacteria, are really going to have a go at this stuff when it gets set.

And, of course, that's the issue, is that a lot of that has already happened by the time it gets into the marsh. So we are not seeing the kind of classic, oily slick. We are seeing this already degraded kind of chocolate-brown material a lot of the time - or obviously, a lot of tar balls, too.

PALCA: Okay. Let's take another call now and go to Sara in Libertyville, Illinois. Sara, you're on the air with SCIENCE FRIDAY.

SARA (Caller): Hi. I am really I don't understand the whole concept of oil evaporating. Can you explain it to me? Because I thought that I mean, I thought, like, water evaporates, and then a solid would be leftover there. And wouldn't that still cause problems?

PALCA: Well, okay, let's see if we - Chris Reddy, maybe you want to tackle that one.

Dr. REDDY: Sure. Think about that, if first of all, it's crude oil, and so crude oil is made up of a variety of compounds that we use and refine to make gasoline, all the way up to asphalt that you put on the road.

So it's a really good question. What is evaporating are the compounds that are most likely to evaporate, and so if you dropped a gallon of gasoline on the road, you would see a lot of it evaporate, because those are the properties that lead to it.

If you dump some asphalt on the road, not much of it would evaporate and go away. And so what's happening right now in the Gulf is what we call weathering, which is that selective compounds are getting removed by evaporation. But it's not- it's not a complete blanket, that every, single molecule that's in the oil is evaporating at the same rate, or will evaporate at all.

So the end result is is that the oil is constantly changing due to a variety of processes. Evaporation is most likely the most biggest driving force at this point in terms of nature's ability to help clean up the spill.

PALCA: Okay, thanks for clearing that up. Dr. Reed, can I come back to you and ask: What was the circumstance in the Gulf Coast before this? Were things in trouble? Were they getting better? You know, give us a sense of how were the status quo ante, as it were.

Dr. REED: Well, the coast of Louisiana certainly was already in a very, very badly degraded state before this spill, and this is just another insult of many that have been thrown at it over the last few decades.

Yes, we have lost hundreds and hundreds of square miles of land to open water in the last 50 years, and the coast is falling apart like a kind of Swiss cheese effect, with the interior areas of the marsh just opening up to open water.

And so we have been working very hard here in Louisiana to try and get large-scale restoration, really try to rebuild our landscape and make it much more resilient for the future. And that really has been the focus of government officials and scientists and everybody around the same table here for the last decade.

This event has been a little bit of a distraction for us, but we know it just makes it even more urgent to get back on to large-scale restoration.

PALCA: Okay. Let's take another call now and go to Currin(ph) in Ann Arbor, Michigan. Currin, welcome to SCIENCE FRIDAY. You're on the air.

CURRIN (Caller): Hi. I've been wondering about the disposal of all of the residue from this that's landing on beaches and being put into plastic bags and all the plastic gloves that people are using and all of those barrier things that are keeping - trying to keep the oil from reaching the reeds.

PALCA: You mean there's a lot of we're getting a lot of garbage we have to throw away.

CURRIN: That's right. And - but mostly, like, can any of the oil be recovered when it's sucked into those, oh, those absorbent things?

PALCA: I don't know. Let me see if one of our guests knows the answer to that. Chris Reddy, maybe?

Dr. REDDY: Well, I'm certainly not an expert on the response and cleanup aspects, but, you know, we have to balance some of these efforts that are unfortunate that we have to, you know, use and waste sponges or equivalent to pick up oil.

But it has to be balanced with the overall goal after an oil spill, which is to, quote, "reduce damages." And so, in some cases, it may be frustrating that we're using a lot of plastic gloves and Tyvek suits to clean up the coastline, but we have tradeoffs in terms of trying to diminish the overall impact to the environment.

And so these decisions are made that you have to do this, and hopefully the net result is that we have a better environment due to this response and having to pick up oiled rocks and perhaps throw them away.

PALCA: Okay. We have time for another call, I think. Let's go to David in Chicago, Illinois. David, welcome to SCIENCE FRIDAY.

DAVID (Caller): Hi, good afternoon. Thanks for taking my call.

PALCA: Sure.

DAVID: Much has been made about trying to estimate the magnitude of the entire spill, and obviously, you can have the visible evidence of that which makes landfall and gets into the reeds, onto animals and such.

But there must be an enormous amount that's still in the water column that is going to be difficult to track and difficult to understand what actually happens to it. What kind of efforts are being made to understand that phenomena?

Dr. REDDY: There have been hundreds and hundreds of water samples that have been collected and that are in the pipeline, per se, for analysis. We certainly don't live in the real world of crime scene investigation TV shows.

So it takes a long time for the samples to be collected, brought back to land, analyzed. They go through several rounds of quality control.

I think what's going to happen here, in the next, maybe, six weeks, 12 weeks and months, are gaps are going to get started to fill in, like filling in a crossword - a jigsaw puzzle, and starting to see where we might see oil below the surface and start to have a little bit better feel for the three-dimensional aspect.

And with that data, we'll start to be able to balance this checkbook of oil that was released into what compartments that it went to. But at this time, I think that a lot of data, a lot of samples are collected, and it just takes time for them to go through the pipeline.

PALCA: Okay. Denise Reed, I want to throw the last question to you. You know, we're in, I suppose, and we certainly face a couple months of hurricane season in the Gulf of Mexico and throughout the Southern Atlantic and Caribbean. What do you think the what would happen? How badly would things how much worse off would things be if a hurricane hit the Gulf right now, hit the Gulf Coast?

Dr. REED: Well, the good news is that we don't have a continuing supply of oil to the surface anymore. So the large areas of oil residue on the surface of the water are now no longer present in the great quantities that they were before.

The big worry with the marshes when we have a hurricane is, as I said earlier, under normal circumstances, the tide only goes up and down by the foot or so, and so the plants actually catch the oil at the edge. When we have a hurricane or even a tropical storm, then obviously, the water gets a lot deeper, and that can spread what we have on the surface the oil over - on the surface of the water over a much, much larger area. Of course, the wave action tends to kind of break it up and fragment it, as well, so it's not like we have a - would have a big slick moving across the surface of the marsh.

But I have to say that having lived here for more than 20 years, when people's houses flood during a hurricane, they have enough to deal with in terms of hosing the mud out of their house and dealing with all of those issues without having to be concerned about whether there is oil in that water and oil in that mud. And so we've got to cross our fingers. That that would be a whole different kind of problem than the problems we've been dealing with for the last hundred days, and let's just hope it doesn't happen.

PALCA: Exactly. Well, the Gulf has had a feeling of being snake bit. Hopefully, they'll avoid that particular problem this year. But anyway, we've run out of time. I'd like to thank you both. Christopher Reddy is an associate scientist of marine chemistry and geochemistry at the Woods Hole Oceanographic Institution in Massachusetts. Thank you.

Dr. REDDY: And thank you, Joe.

PALCA: And Denise Reed, who you were just hearing, is the interim director of the Pontchartrain Institute for Environmental Sciences at the University of New Orleans and a professor in the Department of Earth and Environmental Sciences there. Thank you.

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